bmills at alumni.cmu.edu
Sat Feb 4 12:07:41 PST 2012
> > From: Bryan Mills <bmills at alumni.cmu.edu>
> > To: David L Wetzell <wetzelld at gmail.com>
> > > If there are 3-5 seats STV then the number of candidates won't
> > proliferate
> > > too much and there'd be 5-7 places to vote. This would keep things
> > > reasonable.
> > To get reasonable proportionality with only 3-5 seats per district
> > you'd probably need to go to an MMP system, with all its added
> > complexity. Otherwise Droop proportionality doesn't buy you much over
> > FPTP; with 5 seats the Droop quota measures to a precision of ~17%,
> > and the remaining 17% in each district is still susceptible to
> > gerrymandering.
> Not much?
> The goal here is not perfectionism wrt proportionality.
> The goal is to increase proportionality and to increase the number of
> competitive seats
> and to reduce the cut-throat competitive nature of US political rivalry
> between its two biggest parties
> so they can't dominate the other and have more incentives thereby to work
> together on the many issues that need work.
I'm doubtful that 3-5 candidate districts actually would "increase the
number of competitive seats". Each major party ends up with 1-2 safe
seats, and at that level of granularity gerrymandering and geographical
polarization are still significant enough to render the last seat
non-competitive in most districts. (It would increase proportionality
somewhat - by transforming some of the safe-by-gerrymandering seats into
safe-by-Droop-proportionality seats - but you seem to be arguing that
proportionality isn't as important as competition.)
Suppose we have two parties with a 50/50 split and 5 seats per district,
with one party more popular in urban areas and one more popular in rural
areas. And suppose that the district lines are drawn such that 4/5 of
districts are slightly more rural than average and 1/5 of districts are
more urban than average, so that the 5th seat in each district becomes
relatively safe as well. (We can do this fairly easily using geographical
boundaries by centering 1/5 of the districts around cities.)
Scale that up to 400 legislators (80 districts). What do we end up with?
320 "natural" safe seats guaranteed by Droop proportionality (160 for each
80 gerrymandered-safe seats for the rural party
20 gerrymandered-safe seats for the urban party
Now, despite a 50/50 natural split, the rural party has a 60%
supermajority. And, of course, if you draw the district lines differently
you can do the same thing for the urban party.
So there's still relatively little hope that a system with such small
districts would produce a party-proportional legislature. As you point out
elsewhere, it might still be possible to get an ideologically-proportional
legislature if you can get the parties themselves to shift ideologies.
> If you assume two major parties with ~40% of the electorate each, that
> > means that the 5th seat in each district is noisy -- but it's not
> > random noise, it's systematically biased by the parties' voting
> > strategies and the choice of district boundaries. Larger districts
> > allow finer-grained Droop quotas and thereby reduce that noise.
> dlw: Smaller districts engender less opposition from those in power.
> They keep the constituent-legislator relationship more so.
Absolutely agreed that smaller districts engender less opposition from
those in power. That's because smaller districts don't fix the biases that
keep them in power.
They do maintain the constituent-legislator relationship, *for the subset
of voters who voted in favor of the legislator*. For the remaining Droop
quota of un- or under-represented constituents the nonexistence of the
constituent-legislator relationship is also maintained.
> >> But if we assume that partial rankings are effective, there's still the
> > >> strategy/computation tradeoff to deal with: allowing truncated ballots
> > >> still doesn't help with favorite-betrayal, and STV variants less
> > >> susceptible to favorite-betrayal are also less susceptible to
> > >> counting.
> > >>
> > >
> > > dlw: Truncated ballots may not end favorite betrayal, but it'll help
> > > it.
> > I don't see how; please elaborate.
> This is essentially the same arg that IRV does not end the fact that some
> will still on occasion be pressured to betray their favorite.
> But it'll be of less consequence when it happens. It won't be 3rd party
> dissenters, it'll be the supporters of a major party that does
> not position itself near the true political center who get pressured to
> betray their favorite and that in turn will pressure the major party
> to adapt or die.
Are you saying that favorite-betrayal isn't a problem when those forced to
do it belong to a major party? I hope I'm just misunderstanding your
point, but it sounds to me like you're describing a system like FPTP but
with major-party spoilers substituted for minor-party spoilers.
> >> With an implicit "first-preference" approval, it has the same problem
> > >> traditional STV (i.e. IRV), namely of unduly rewarding
> > favorite-betrayal.
> > >> With an implicit "all-ranked" approval, the overall system would
> > >> violate later-no-harm with much higher frequency; by expressing a
> > >> preference between two dispreferred candidates one might
> > >> put the higher of the two in contention.
> > >>
> > >
> > > dlw: I'd say empirically we'd see just how high of a frequency LNH
> > be
> > > violated. Jameson Quinn had a hard time coming up with a pathological
> > > example for IRV3/AV3 and I imagine it'd be similar for the above. The
> > 1st
> > > stage would reduce the number of candidates to N+2 and it seems likely
> > that
> > > the N+2nd and N+3rd candidates in terms of "all-ranked" approval are
> > > likely to be among the N winners.
> > Hmm, ok. I'm operating on the assumption that voters will vote
> > strategically if doing so is easy, and will vote approximately
> > honestly if strategic voting is difficult.
> > We're taking the top S+k winners and running some ideal STV method on
> > them; let's try to find an "easy" strategy. Here's my idea:
> > 1) Gather a set of related parties to form a majority-coalition.
> > 2) Have the coalition propose exactly S+k candidates.
> good luck coordinating that..
> 3) Ask coalition voters to vote for all of the coalition candidates in
> > any order they choose.
> > Since a majority of candidates approve of every coalition candidate
> > and disapprove of every competing candidate, the coalition candidates
> > win the approval vote.
> > By adding the "approval" phase to the STV election, I'm able to turn a
> > simple majority into a 100% supermajority.
> > Is there a flaw in my strategy? (I don't think there is, but I may be
> > missing something.) If not, we'll either need to abandon a fixed
> > limit on the number of candidates or we'll need something more
> > sophisticated than a simple approval-vote to filter them.
> dlw: It's not realistic.
> You'd need to have serious intra-party discipline to keep the no. of
> candidates down to S+2
> and to get a majority of voters all to vote for all of that S+2 candidates.
> That is a serious coordination problem.
> But if it did happen then it'd "work" in terms of making the leading
> coalition of parties cast a broad net that strongly met the needs of most
> people. This would be much better than a bunch of non-competitive
> single-winner elections. In that case, we're in DINO land.
By "strongly met the needs of most people" you appear to mean "met the
needs of a bare majority of people marginally better than the
alternatives". My concern is that in this scenario 25% of the electorate
would benefit substantially, 25% would benefit marginally, and the
remaining 50% would be arbitrarily worse off. That's essentially the same
worst-case behavior as the current majority-of-majorities setup, but with a
simpler strategy required to implement it.
That being the case, I think we'd be better off with small-district STV
than with large-district STV with this sort of approval-based filtering.
> >> It may well be that these issues are all less severe than in the
> > >> deterministic alternatives to STV, but I still think they're enough to
> > >> merit consideration of nondeterministic alternatives.
> > >>
> > >
> > > In terms of the US's political culture, nondeterministic alternatives
> > > not going to happen anytime in the near future and we need electoral
> > reform
> > > ASAP!!!!
> > Sadly, I think both nondeterminism and STV share the "not going to
> > happen in the near future given political culture in the US"
> > classification, given that US law requires single-winner FPTP
> > elections for federal representation and the major parties (who
> > control the legislature and benefit greatly from FPTP) have no
> > incentive to change that law.
> dlw: STV need not end 2-party domination. Reforms that do not end 2-party
> domination are more fit in the US and should be the only ones pushed.
> And, as I've shown, it's implementation can be simplified.
> Thus, it can become a political jujitsu issue, whereby it is more rational
> for those in power to accommodate than to resist the proposed change.
The belief that the 2-party system can accurately reflect voter consensus
relies heavily on the assumption that voters' differences of opinions
correlate sufficiently well with a single dimension of variability, so that
tending toward the center along a single axis produces centrist results on
all issues. I do not accept that assumption: in my experience, Americans
disagree along at least two axes that do not correlate perfectly (fiscal
policy and social policy).
> So as far as I can tell the only option for meaningful reform is a
> > constitutional amendment, and that means reforming 75% of the states
> > as a first step. This is not a short-term process.
> I think one could argue that the current law requiring single-winner
> elections is discriminatory twds minorities, and adopted under bad
> circumstances, and thereby unconstitutional. This would not require a
> constitutional amendment.
I think you're perhaps overly optimistic about the willingness of courts to
overturn election law. But we'll see - I'd be thrilled to be proven wrong
about this one.
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